"Why Always Me?" read the lament on Mario Balotelli's T-shirt. "Why Always Them?" Manchester City fans have complained about United for generations.

Not any more. The second-best side in Europe after their Champions League final defeat to Barcelona, United now face a struggle to be seen as the No1 team in their own metropolis after their noisy neighbours made a grab for power with this stunning 6-1 victory.

"There's a lot of embarrassment in the dressing room and rightly so," Sir Alex Ferguson said after City moved five points clear of them in the Premier League, with 33 goals in nine games. With a little help from an Abu Dhabi multibillionaire, the downtrodden have shaken off their chains. City overran United through the brilliance of David Silva and the icy finishing of Balotelli and Edin Dzeko.

First Balotelli ignited his own house by launching fireworks through his bathroom window, then he threw a match on the old order, vindicating Roberto Mancini's decision to start him with City's first two goals. United's most optimistic followers will dismiss this as a freakish result caused partly by the dismissal of Jonny Evans on 46 minutes for a last-man foul on Balotelli. But it went much deeper. City were regal: skilful and strong in equal parts as they ran in three late goals inside four minutes to turn a win into a massacre.

Not since 1968, arguably, has there been so much individual talent on show in a Manchester derby. The additions of Silva, Sergio Agüero and Samir Nasri to a powerful but sometimes mechanical City side have transformed England's highest league and jeopardised United's dominance. Long gone are the days when City's disciples took refuge in fatalism and humour. Now they watch Silva bamboozle the best opponents, salute rigorous defending and applaud Balotelli as he lifts his jersey to reveal a comedy T-shirt.

Why always him? The red cards, frivolous backheels, motoring incidents and pyrotechnic mishaps may have something to do with it. A persecution complex was no hindrance to him, though, in the home of England's champions. Two minutes before he scored, Balotelli had answered back to Mancini, who was unhappy with his movement. His next act was to capitalise on some typically slick City interplay as he slid the first of City's half-dozen past David de Gea, the goalkeeper in United's worst Premier League defeat.

Never in his long reign has Ferguson conceded that "3-1 or 4-1" would have been a mercy. He described himself as "shattered" and said: "I can't believe it. It was incredibly disappointing. The sending off was the killer blow. After that they just kept on attacking. We showed a bit of inexperience at the back. At 3-1 or 4-1 we should have settled for that. Our two-full backs were playing as wingers and left us two on three at the back. That was suicidal."

This defeat, Ferguson said, would "leave an impact on the players", who have taken a switchback ride since winning the club's 19th English title in May. Deprived of the ball for most of Barcelona's dazzling Champions League win, they added Ashley Young, Phil Jones and De Gea in the summer, started brightly, whacked Arsenal 8-2 at the end of August and then walked into this ambush: the first six-goal concession at home in the top flight since 1930.

For Ferguson's squad to recover they will need to somehow frame this setback as a freakish product of their own recklessness in chasing a lost game against first-rate counterattackers. But the match also highlighted United's weaknesses, especially an absence of artistry and ingenuity in midfield, where Anderson plodded and Nani, often a match-winner, was anonymous.

At the back United were ripped apart, especially on their left-hand side, where James Milner, Micah Richards and especially Silva caused havoc as United's team shape fell apart. "Sheikh Mansour, m'lord," City fans chanted, like a rugby crowd. And: "The city is ours," followed by a fruity exhortation to United's followers to "go back to London". These old taunts assumed a fresh sharpness coming from a wedge of fans who used to think of trips to Old Trafford as a survival exercise. United will be more dynamic in midfield when Tom Cleverley returns and less limp when Ferguson has had his say at the inquest. But they will not want a second helping of the queasiness they felt when Barcelona taught them a lesson at Wembley. Playing the fall guys to the best team of their age is pretty much unavoidable in present circumstances. This is different.

This was United being usurped on their own manor. How, they will ask, did City get so good?

United's board will brace itself for a regurgitation of ominous statistics, principally the one showing the £473m the Glazer family have drained in bank interest, fees and charges. The juxtaposition of two ownership models now favours City. In one, debt is loaded on the club to pay. In the other, money pours in as gift, as extravagance.

This season has brought a vital change in the outside view of City, who occupy the commanding heights despite having to deal with Carlos Tevez's apparent wildcat strike in Munich. The neutral can watch Silva, Nasri and Agüero for sheer entertainment value. This was the trick Sheikh Mansour needed to pull off: to draw converts to an idea beyond and above mere power and money.

With their mohicans (Balotelli, Micah Richards), physical might (Yaya Touré, Vincent Kompany), industry and creativity, City have cuffed away the charge that they had yet to face anyone serious in this Premier League campaign. They have established a precedent against top-four opposition they will need to maintain when the final third of the season tests their togetherness and cunning.

United, on the other hand, have faced down threats over the last 15 years from Arsène Wenger's Arsenal, Roman Abramovich's Chelsea and a resurgent Liverpool. This one is so close they can smell it, across town. It is inescapable on the streets and in the daily life of Manchester. Stand well back, and enjoy.

Sir Alex Ferguson described his team's 6-1 defeat in Sunday's Manchester derby as the 'worst result in my history'. It probably was, but it was not the first time United have suffered a heavy defeat in the Premier League era